The invention concerns a burner for burning gaseous and/or liquid fuels in a narrow combustion space.
A burner of this type is employed for the low-NO.sub.x combustion of fuels. The formation of nitrogen oxides is suppressed in a known burner (German OS 3 327 597) by supplying air discontinuously and exploiting it to generate an injector action that forces extensively burned-out flue gases out of the combustion space. The flue gases are forwarded to the point where flaming is initiated between the primary-air and secondary-air intakes. Since this known burner is employed to heat large combustion spaces, the air line and the flue-gas recirculation channel are located in the burner flute outside the combustion space to protect them from the heat.
In narrow combustion chambers of the type demarcated by the flame tube of a flame-tube boiler that is heated by a burner, the substances flowing out of the burner tend to piston. A flow of this type loses subsidiary currents that contain incompletely burned-out flue gas. In the method employed with flame-tube boiler burners of the type disclosed in German OS 3 327 597 accordingly, the incompletely burned-out gas is forwarded to the flame-initiation point. This approach, however, does not completely attain the object of extensively suppressing the formation of nitrogen oxides.